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Python Code to communicate with the 6 channel Pfeiffer Vacuum TPG256A MaxiGauge pressure gauge controller via a serial connection
#!/usr/bin/env python
### Load the module:
from PfeifferVacuum import MaxiGauge, MaxiGaugeError
import time
import sys
### Initialize an instance of the MaxiGauge controller with
### the handle of the serial terminal it is connected to
mg = MaxiGauge('/dev/ttyUSB1')
### Read out the pressure gauges
while True:
startTime = time.time()
try:
ps = mg.pressures()
except MaxiGaugeError, mge:
print mge
continue
line = ""
for sensor in ps:
#print sensor values
if sensor.status in [0,1,2]: # if normal, over or under range
line += str(sensor.pressure)
line += ", "
print line[0:-2] # omit the last comma and space
sys.stdout.flush()
# do this every second
endTime = time.time()-startTime
time.sleep(max([0.0, 1.0-endTime]))
#!/usr/bin/env python
### Load the module:
from PfeifferVacuum import MaxiGauge
### Initialize an instance of the MaxiGauge controller with
### the handle of the serial terminal it is connected to
mg = MaxiGauge('/dev/ttyUSB0')
### Run the self check (not needed)
print(mg.checkDevice())
### Set device characteristics (here: change the display contrast)
print("Set the display contrast to: %d" % mg.displayContrast(10))
### Read out the pressure gauges
print(mg.pressures())
### Display the value of the pressure gauges for 20 repeated read outs
for i in range(20):
ps = mg.pressures()
print "Sensor 1: %4e mbar" % ps[0].pressure + "Sensor 6: %4e mbar" % ps[5].pressure
#!/usr/bin/env python
# -*- encoding: UTF8 -*-
# Author: Philipp Klaus, philipp.l.klaus AT web.de
# This file is part of PfeifferVacuum.py.
#
# PfeifferVacuum.py is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# PfeifferVacuum.py is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with PfeifferVacuum.py. If not, see <http://www.gnu.org/licenses/>.
### This module depends on PySerial, a cross platform Python module
### to leverage the communication with the serial port.
### http://pyserial.sourceforge.net/pyserial.html#installation
### If you have `pip` installed on your computer, getting PySerial is as easy as
### pip install pyserial
import serial
class MaxiGauge (object):
def __init__(self, serialPort, baud=9600, debug=False):
self.debug=debug
try:
self.connection = serial.Serial(serialPort, baudrate=baud, timeout=0.2)
except serial.serialutil.SerialException as se:
raise MaxiGaugeError(se)
#self.send(C['ETX']) ### We might reset the connection first, but it doesn't really matter:
def checkDevice(self):
message = "The Display Contrast is currently set to %d (out of 20).\n" % self.displayContrast()
message += "Keys since MaxiGauge was switched on: %s (out of 1,2,3,4,5).\n" % ", ".join( map (str, self.pressedKeys()) )
return message
def pressedKeys(self):
keys = int(self.send('TKB',1)[0])
pressedKeys = []
for i in [4,3,2,1,0]: # It's got 5 keys
if keys/2**i == 1:
pressedKeys.append(i+1)
keys = keys%2**i
pressedKeys.reverse()
return pressedKeys
def displayContrast(self,newContrast=-1):
if newContrast == -1: return int(self.send('DCC',1)[0])
else: return int(self.send('DCC,%d' % (newContrast,) ,1)[0])
def pressures(self):
return [self.pressure(i+1) for i in range(6)]
def pressure(self, sensor):
if sensor < 1 or sensor >6: raise MaxiGaugeError('Sensor can only be between 1 and 6. You choose ' + str(sensor))
reading = self.send('PR%d' % sensor, 1) ## reading will have the form x,x.xxxEsx <CR><LF> (see p.88)
try:
r = reading[0].split(',')
status = int(r[0])
pressure = float(r[-1])
except:
raise MaxiGaugeError("Problem interpreting the returned line:\n%s" % reading)
return PressureReading(sensor, status, pressure)
def debugMessage(self, message):
if self.debug: print(repr(message))
def send(self, mnemonic, numEnquiries = 0):
self.connection.flushInput()
self.write(mnemonic+LINE_TERMINATION)
#if mnemonic != C['ETX']: self.read()
#self.read()
self.getACQorNAK()
response = []
for i in range(numEnquiries):
self.enquire()
response.append(self.read())
return response
def write(self,what):
self.debugMessage(what)
self.connection.write(what)
def enquire(self):
self.write(C['ENQ'])
def read(self):
data = ""
while True:
x = self.connection.read()
self.debugMessage(x)
data += x
if len(data)>1 and data[-2:]==LINE_TERMINATION:
break
return data[:-len(LINE_TERMINATION)]
def getACQorNAK(self):
returncode = self.connection.readline()
self.debugMessage(returncode)
## The following is usually expected but our MaxiGauge controller sometimes forgets this parameter... That seems to be a bug with the DCC command.
#if len(returncode)<3: raise MaxiGaugeError('Only received a line termination from MaxiGauge. Was expecting ACQ or NAK.')
if len(returncode)<3: self.debugMessage('Only received a line termination from MaxiGauge. Was expecting ACQ or NAK.')
if len(returncode)>2 and returncode[-3] == C['NAK']:
self.enquire()
returnedError = self.read()
error = str(returnedError).split(',' , 1)
print repr(error)
errmsg = { 'System Error': ERR_CODES[0][int(error[0])] , 'Gauge Error': ERR_CODES[1][int(error[1])] }
raise MaxiGaugeNAK(errmsg)
#if len(returncode)>2 and returncode[-3] != C['ACQ']: raise MaxiGaugeError('Expecting ACQ or NAK from MaxiGauge but neither were sent.')
if len(returncode)>2 and returncode[-3] != C['ACQ']: self.debugMessage('Expecting ACQ or NAK from MaxiGauge but neither were sent.')
# if no exception raised so far, the interface is just fine:
return returncode[:-(len(LINE_TERMINATION)+1)]
def disconnect(self):
#self.send(C['ETX'])
if hasattr(self, 'connection') and self.connection: self.connection.close()
def __del__(self):
self.disconnect()
class PressureReading(object):
def __init__(self, id, status, pressure):
if int(id) not in range(1,7): raise MaxiGaugeError('Pressure Gauge ID must be between 1-6')
self.id = int(id)
if int(status) not in PRESSURE_READING_STATUS.keys(): raise MaxiGaugeError('The Pressure Status must be in the range %s' % PRESSURE_READING_STATUS.keys())
self.status = int(status)
self.pressure = float(pressure)
def statusMsg(self):
return PRESSURE_READING_STATUS[self.status]
def __repr__(self):
return "Gauge #%d: Status %d (%s), Pressure: %f mbar\n" % (self.id, self.status, self.statusMsg(), self.pressure)
### ------ now we define the exceptions that could occur ------
class MaxiGaugeError(Exception):
pass
class MaxiGaugeNAK(MaxiGaugeError):
pass
### ------- Control Symbols as defined on p. 81 of the english
### manual for the Pfeiffer Vacuum TPG256A -----------
C = {
'ETX': "\x03", # End of Text (Ctrl-C) Reset the interface
'CR': "\x0D", # Carriage Return Go to the beginning of line
'LF': "\x0A", # Line Feed Advance by one line
'ENQ': "\x05", # Enquiry Request for data transmission
'ACQ': "\x06", # Acknowledge Positive report signal
'NAK': "\x15", # Negative Acknowledge Negative report signal
'ESC': "\x1b", # Escape
}
LINE_TERMINATION=C['CR']+C['LF'] # CR, LF and CRLF are all possible (p.82)
### Mnemonics as defined on p. 85
M = [
'BAU', # Baud rate Baud rate 95
'CAx', # Calibration factor Sensor x Calibration factor sensor x (1 ... 6) 92
'CID', # Measurement point names Measurement point names 88
'DCB', # Display control Bargraph Bargraph 89
'DCC', # Display control Contrast Display control contrast 90
'DCD', # Display control Digits Display digits 88
'DCS', # Display control Screensave Display control screensave 90
'DGS', # Degas Degas 93
'ERR', # Error Status Error status 97
'FIL', # Filter time constant Filter time constant 92
'FSR', # Full scale range of linear sensors Full scale range of linear sensors 93
'LOC', # Parameter setup lock Parameter setup lock 91
'NAD', # Node (device) address for RS485 Node (device) address for RS485 96
'OFC', # Offset correction Offset correction 93
'OFC', # Offset correction Offset correction 93
'PNR', # Program number Program number 98
'PRx', # Status, Pressure sensor x (1 ... 6) Status, Pressure sensor x (1 ... 6) 88
'PUC', # Underrange Ctrl Underrange control 91
'RSX', # Interface Interface 94
'SAV', # Save default Save default 94
'SCx', # Sensor control Sensor control 87
'SEN', # Sensor on/off Sensor on/off 86
'SPx', # Set Point Control Source for Relay xThreshold value setting, Allocation 90
'SPS', # Set Point Status A,B,C,D,E,F Set point status 91
'TAI', # Test program A/D Identify Test A/D converter identification inputs 100
'TAS', # Test program A/D Sensor Test A/D converter measurement value inputs 100
'TDI', # Display test Display test 98
'TEE', # EEPROM test EEPROM test 100
'TEP', # EPROM test EPROM test 99
'TID', # Sensor identification Sensor identification 101
'TKB', # Keyboard test Keyboard test 99
'TRA', # RAM test RAM test 99
'UNI', # Unit of measurement (Display) Unit of measurement (pressure) 89
'WDT', # Watchdog and System Error Control Watchdog and system error control 101
]
### Error codes as defined on p. 97
ERR_CODES = [
{
0: 'No error',
1: 'Watchdog has responded',
2: 'Task fail error',
4: 'IDCX idle error',
8: 'Stack overflow error',
16: 'EPROM error',
32: 'RAM error',
64: 'EEPROM error',
128: 'Key error',
4096: 'Syntax error',
8192: 'Inadmissible parameter',
16384: 'No hardware',
32768: 'Fatal error'
} ,
{
0: 'No error',
1: 'Sensor 1: Measurement error',
2: 'Sensor 2: Measurement error',
4: 'Sensor 3: Measurement error',
8: 'Sensor 4: Measurement error',
16: 'Sensor 5: Measurement error',
32: 'Sensor 6: Measurement error',
512: 'Sensor 1: Identification error',
1024: 'Sensor 2: Identification error',
2048: 'Sensor 3: Identification error',
4096: 'Sensor 4: Identification error',
8192: 'Sensor 5: Identification error',
16384: 'Sensor 6: Identification error',
}
]
### pressure status as defined on p.88
PRESSURE_READING_STATUS = {
0: 'Measurement data okay',
1: 'Underrange',
2: 'Overrange',
3: 'Sensor error',
4: 'Sensor off',
5: 'No sensor',
6: 'Identification error'
}
#!/usr/bin/env python
### Load the module:
from PfeifferVacuum import MaxiGauge, MaxiGaugeError
import time
import sys
### Initialize an instance of the MaxiGauge controller with
### the handle of the serial terminal it is connected to
mg = MaxiGauge('/dev/ttyUSB1')
logfile = file('measurement-data.txt', 'a')
### Read out the pressure gauges
while True:
startTime = time.time()
try:
ps = mg.pressures()
except MaxiGaugeError, mge:
print mge
continue
line = ""
for sensor in ps:
#print sensor
if sensor.status in [0,1,2]:
line += "%.3E" % sensor.pressure
line += ", "
print line[0:-2] # omit the last comma and space
sys.stdout.flush()
logfile.write(line+'\n')
logfile.flush()
# do this every second
endTime = time.time()-startTime
time.sleep(max([0.0, 1. - endTime]))
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